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We present a design and the optimization of an irregular-shaped ring-pair magnet array that generates a 1D monotonic field pattern for 2D head imaging in a low-field portable MRI system. The magnet rings are discretized into fan-shaped ring…

Medical Physics · Physics 2019-01-08 Zhi Hua Ren , Jia Gong , Shao Ying Huang

We describe a framework to assemble permanent-magnet cubes in 3D-printed frames to construct dipole, quadrupole, and solenoid magnets, whose field, in the absence of iron, can be calculated analytically in three spatial dimensions. Rotating…

Accelerator Physics · Physics 2021-12-06 Volker Ziemann

A common scientific inverse problem is the placement of magnets that produce a desired magnetic field inside a prescribed volume. This is a key component of stellarator design, and recently permanent magnets have been proposed as a…

Plasma Physics · Physics 2022-10-05 Alan A. Kaptanoglu , Tony Qian , Florian Wechsung , Matt Landreman

We present a target field approach to analytically design magnetic fields using permanent magnets. We assume that their magnetisation is bound to a two-dimensional surface and is composed of a complete basis of surface modes. By posing the…

Applied Physics · Physics 2024-05-24 Peter J. Hobson , Chris Morley , Alister Davis , Thomas Smith , Mark Fromhold

Magnetars are highly magnetized neutron stars whose magnetic dipole ranges from $10^{14}$ to $10^{15}$ G. The MRI is considered to be a promising mechanism to amplify the magnetic field in fast-rotating protoneutron stars and form…

High Energy Astrophysical Phenomena · Physics 2021-01-27 Alexis Reboul-Salze , Jérôme Guilet , Raphaël Raynaud , Matteo Bugli

A permanent magnet array (PMA) is a preferred source of magnetic field for body-part-dedicated low-field (<0.5 T) portable magnetic resonance imaging (MRI) because it has a small footprint, no power consumption, and no need for a cooling…

Medical Physics · Physics 2022-11-23 Ting-Ou Liang , Yan Hao Koh , Tie Qiu , Erping Li , Wenwei Yu , Shao Ying Huang

A novel design is presented for a permanent magnet array to address specific challenges with scalable trapped-ion quantum computing systems. Design and optimization of this magnet geometry is motivated by concepts for large-scale Quantum…

Quantum Physics · Physics 2026-04-06 Mitchell G. Peaks

Persistent currents and magnetization are considered for a two-dimensional electron (or gas of electrons) coupled to various magnetic fields. Thermodynamic formulae for the magnetization and the persistent current are established and the…

Condensed Matter · Physics 2009-10-31 Jean Desbois , Stephane Ouvry , Christophe Texier

The application of quadrupole-devices with high field gradients and small apertures requires precise control over higher order multipole field components. We present a new scheme for performance control and tuning, which allows the…

Instrumentation and Detectors · Physics 2009-11-09 S. Becker , M. Bussmann , S. Raith , M. Fuchs , R. Weingartner , P. Kunz , W. Lauth , S. Schramm , M. El Ghazaly , F. Grüner , H. Backe , D. Habs

We optimised the magnetic field homogeneity of two canonical designs for mobile microfluidic NMR applications: two parallel magnets with an air gap and a modified Halbach array. Along with the influence of the sample length, general design…

Applied Physics · Physics 2021-03-26 Yannick Klein , Leon Abelmann , Han Gardeniers

A method to create a highly homogeneous magnetic field by applying topology optimized, additively manufactured shimming elements is investigated. The topology optimization algorithm can calculate a suitable permanent and nonlinear soft…

Applied Physics · Physics 2018-04-17 C. Huber , M. Goertler , F. Bruckner , C. Abert , I. Teliban , M. Groenefeld , D. Suess

Halbach magnets are a source of homogeneous magnetic field in an enclosed volume while keeping stray fields at a minimum. Here, we present the design, construction, and characterization for a 10 cm inner diameter double Halbach ring…

Instrumentation and Detectors · Physics 2021-02-24 Arne Wickenbrock , Huijie Zheng , Georgios Chatzidrosos , Joseph Shaji Rebeirro , Tim Schneemann , Peter Bluemler

Purpose: MRI gradients with a conventional, bipolar design generally face a trade-off between performance, encoding ambiguity, and circumventing the latter by means of RF selectivity. This problem is particularly limiting in cutting-edge…

We have developed a fast method to design perpendicular permanent magnets for simplifying stellarator coils based on existing codes. Coil complexity is one of the main challenges for stellarators. To date, only electromagnetic coils have…

Plasma Physics · Physics 2020-05-13 Caoxiang Zhu , Michael Zarnstorff , David Gates , Arthur Brooks

A method to realize effective magnetic fields for photons in square lattices of coupled optical waveguides or resonators is suggested, which is inspired by an optical analogue of photon-assisted tunneling of atom optics. It is shown that an…

Quantum Physics · Physics 2013-10-21 Stefano Longhi

Low-field MRI is increasingly considered accessible for imaging owing to its lower cost, simpler infrastructure requirements, and potential for mobile and point-of-care deployment. A central challenge is achieving clinically useful field…

Medical Physics · Physics 2026-04-28 Ivan Etoku Oiye , Ajay Sharma , Sairam Geethanath

Atomic bandpass filters are used in a variety of applications due to their narrow bandwidths and high transmission at specific frequencies. Predominantly these filters in the Faraday (Voigt) geometry, using an applied axial(transverse)…

It is shown that the magnetic-field coils of a stellarator can, at least in principle, be substantially simplified by the use of permanent magnets. Such magnets cannot create toroidal magnetic flux but they can be used to shape the plasma…

Plasma Physics · Physics 2020-03-11 P. Helander , M. Drevlak , M. Zarnstorff , S. C. Cowley

This paper presents the design and experimental characterization of a 1 T electromagnet tailored to meet the demands of a Magnetic Resonance Imaging (MRI) system conceived for spatial resolutions at the level of tens of microns. For high…

Magneto-rotational instability (MRI) is an important instability mechanism for rotating flows with magnetic fields. In particular, when the strength of the magnetic field tends to zero, the stability criterion for rotating flows is…

Analysis of PDEs · Mathematics 2024-10-28 Zhiwu Lin , Yucong Wang , Wenpei Wu